Why hollow glass microspheres can be used as a matting agent in coatings?
The core reason hollow glass microspheres can be used as a matting agent in coatings lies in their micron-sized spherical hollow structure, which creates microscopic surface roughness after film formation, inducing diffuse reflection of light. They also possess the unique advantages of low oil absorption and minimal thickening.
Matting Mechanism Surface Micro-Roughening:
The microsphere particle size (typically 5-50μm for optimal matting) is larger than resin molecules. During drying and curing, some particles protrude from the paint film surface, disrupting the specular smoothness and causing diffuse reflection of incident light instead of specular reflection, thus reducing gloss.
Refractive Index Matching and Scattering:
The refractive index of glass (approximately 1.5) is close to that of common resins (1.4-1.6). Although glass has high transparency, matting is achieved through geometric optical scattering caused by physical protrusions, rather than internal scattering due to refractive index differences.
